A large dataset containing values for fish, algae and Daphnia toxicity for more than 2000 chemical compounds and mixtures was investigated. The dataset was taken from the New Chemicals Data Base of the European Union [provided by the European Chemicals Bureau, Institute for Health and Consumer Protection (http://ecb.jrc.it)]. The data are collected from industry, according to requirements of the EU Council Directive 67/548/EEC as amended for the seventh time by the EU Council Directive 92/32/EEC. The toxicity of neural compounds, salts, metal complexes, as well as compound mixtures has been recorded. A baseline effect is demonstrated by compounds known to act by narcotic mechanisms of action i.e. a relationship is observed between the toxicity and the logarithm of the octanol-water partition coefficient (log P). Prediction of the toxicity of more reactive compounds requires the use of further descriptors.